If my MA had to use two different identities, I would either have her on a WIN7 or XP Pro fast user switching. But, the best way to go would be with a virtual machine. The VM could be minimized with AC running under the other name. You could simply think of the VM as ePrescribe machine. Even name it that. This takes as long as any program to maximize and the program would be ready and able to go. I use virtual machines, and frankly, they are a ton of fun. Plus, you can add another OS or three or thirty. You can use the other OS to play with to try things out.
Of course, you can get free VMs or pay for better ones. The key is you still have to use licensed OS.